The high-voltage electrical equipment or cells used in electrical energy distribution facilities to maneuver and/or protect the electricity grid, are usual modular and/or compact, such that by using a coupling system, such as the one published in document WO235668A1, for example, this electrical equipment may be expanded and therefore any high-voltage electrical arrangement may be obtained.
This expandable electrical equipment or cells have female electrical connection bushings or sockets on their sides, which facilitate the connection between their main bar systems by means of the aforementioned coupling system. In an installation with a plurality of pieces modular electrical equipment connected to one another, the first and/or last piece of electrical equipment in the installation constitutes the connection and/or output of the installation. This connection or outlet of the installation is generally carried out by means of cables with terminals (T- or elbow terminals), which connect to male electrical connection bushings. Given that electrical equipment installed side-by-side comprises female electrical connection bushings, the first and/or last piece of electrical equipment in the installation must have a male electrical connection bushing for the connection and/or output of the installation via cables with terminals.
In an existing on-site installation, it is necessary to give continuity to the electric circuit by connecting to another installation, for example a transformer substation. For this reason, the last piece of electrical equipment must have, on the appropriate side, a male bushing in order to connect the output cables equipped with terminals, or add on another piece of electrical equipment, which involves an added cost. On the whole, all of this involves significant work that includes breakdown and setup time, the sum of costs stemming from labor and from the new electrical equipment with male bushings that must be installed, as well as certain disadvantages from the point of view of logistics, such as increasing the reference quantity and managing product stock. If it is not installed on-site, this means bearing in mind all of these constraints and details when ordering electrical equipment, since some will have female bushings and others male bushings.
Once there is a male bushing on one side of the piece of electrical equipment, it would be necessary to install the cables with connectors (terminals) inside a piece of air-insulated electrical equipment, called a cable riser.
In installations such as wind farms, where the transformer substation may be located inside the mast of the wind turbines, the installation, operation and maintenance of the electrical equipment is conditioned by the width of the door to the tower and by the space available inside it. Therefore, installing this electrical equipment with male bushings along with the cable riser cell could make accessing the inside of the tower problematic, since, due to the narrow width of the tower doors, there are significant limitations for putting in and taking out electrical equipment with male bushings.
Other times, instead of arranging the last piece of electrical equipment or cell with male bushings, the cells with female bushings are maintained, and new electrical equipment called a bus riser cell is installed, which connects to the last cell by means of the aforementioned coupling system. With this gas-insulated bus riser cell it is possible to connect the main bar system to the next installation, making a cable output (with the possibility of including surge arresters) to the next installation.
Moreover, the installation of a new piece of electrical equipment with female bushings and a bus-riser cell involves a higher cost than installing a cable-riser cell, as the latter is a modular air-insulated cell that houses the connection or output cables with terminals, which means that the first and/or last piece of electrical equipment in the installation has to have a male electrical connection bushing.
Also, due to the need to employ electrical equipment with male electrical connecting bushings, for example in order to provide an input or continuity to an installation that forms part of an electric circuit, in addition to standard electrical equipment, i.e. electrical equipment where at least one of the walls comprises at least one female electrical connection bushing, there must be a stock of electrical equipment on hand with both bushing solutions (male and female), which further complicates the whole set of materials and methods necessary to carry out the logistics, for example in terms of activities related to purchasing, production, transportation, storage, maintenance and distribution.
The voltage and current in high-voltage electrical equipment can be measured in the cable compartment through plug-in terminals, for example T-terminals, which may incorporate a capacitive or resistive voltage sensor and an inductive current sensor. To connect these terminals to the voltage and current sensors, the electrical equipment must also have male bushings. The voltage and current may also be measured in the main bar system, and as such, in an installation with standard modular electrical equipment comprising female bushings, measuring the voltage and intensity in the bars entails installing a new piece of electrical equipment or an air-insulated measuring cell, which incorporates voltage and current transformers.
Along these lines, we can cite examples such as those described in the documents WO2010111808A1 and WO2012080522A1, which relate to a connection device between electrical equipment insulated in different media (gas-air). This connection device consists of an insulator comprising a portion which is coupled to a gas-insulated cell and another portion which is coupled to an air-insulated cell, which may be the measuring cell with the voltage and current transformers. But in this case as well, installing a new piece of electrical equipment (a measuring cell) entails space issues in installations with size constraints, as well as driving up costs.